HJT (Heterojunction with Intrinsic Thin layer) cells, also known as heterojunction solar cells, are a hybrid solar cell technology that combines amorphous silicon and crystalline silicon materials. Due to their unique structure and manufacturing process, HJT cells offer several advantages, including high photoelectric conversion efficiency, low temperature coefficient, high bifaciality, and low light-induced degradation.

HJT Cell Structure

HJT cells use N-type monocrystalline silicon as the substrate light absorption layer. After texturing and cleaning, a 5-10 nm intrinsic amorphous silicon film and a doped P-type amorphous silicon layer are deposited on the front side, forming a p-n heterojunction with the silicon substrate. On the rear side, an intrinsic amorphous silicon film and a doped N-type amorphous silicon layer are deposited to create a back surface field. Finally, TCO (Transparent Conductive Oxide) is deposited on both sides, and Ag electrodes are screen-printed onto the TCO.

Technical Advantages of HJT Cells

High Conversion Efficiency

HJT cells have a high theoretical efficiency limit, with laboratory efficiencies reaching 26.81% and commercial efficiencies ranging between 24% and 26%.

Low Temperature Coefficient

HJT cells have a low temperature coefficient of approximately -0.24%/°C, ensuring stable performance in high-temperature environments.

High Bifaciality

HJT cells achieve a bifaciality of over 90%, enhancing rear-side power generation efficiency.

Low Light-Induced Degradation

HJT cells exhibit no LID (Light-Induced Degradation) or PID (Potential-Induced Degradation), ensuring long-term stability.

High Thin-Wafer Compatibility

The symmetrical structure of HJT cells reduces mechanical stress on silicon wafers, improving yield rates during production. The low-temperature process also minimizes wafer warping, enabling thinner wafers and reducing silicon costs.

Short Production Process

The core production process of HJT cells consists of only four steps: cleaning and texturing, amorphous silicon film deposition, TCO deposition, and metallization. This is significantly simpler compared to PERC and TOPCon cells, improving production yield and reducing labor and maintenance costs.

Latest Developments

Capacity Expansion

Global HJT cell production capacity is gradually increasing, with several companies announcing investments in GW-scale HJT projects.

Cost Reduction and Efficiency Improvement

With technological advancements, the production costs of HJT cells are decreasing, driven by innovations such as thinner wafers, silver-coated copper, and low-indium targets.

Industrialization

The industrialization of HJT cells is accelerating, with many photovoltaic manufacturers deploying HJT production lines.

Technical Challenges

Cost Issues

Despite their high efficiency, HJT cells still face higher production costs, particularly in silver paste and equipment investments.

Technical Difficulties

The manufacturing process of HJT cells is relatively complex, requiring precise control over film thickness, uniformity, and crystalline quality. 

Future Outlook

Technological Innovation

HJT cell technology continues to advance, with improvements such as micro-crystallization to enhance efficiency and optimized module processes to increase power generation.

Market Penetration

As costs decrease and efficiencies improve, HJT cells are expected to capture a larger share of the photovoltaic market in the future. 

Investment Advice

Focus on Leading Companies

Investors should pay attention to companies with significant advantages and strategic deployments in HJT cell technology.

Industry Chain Opportunities

Early-stage equity investment opportunities in the HJT cell supply chain, particularly in equipment manufacturing and material supply, are worth considering.

In summary, HJT cell technology, with its high efficiency and low degradation rates, is considered one of the future directions for the photovoltaic industry. With ongoing technological advancements and cost reductions, HJT cells are expected to achieve broader commercial applications in the coming years.